Cardboard boxes for gift and merchandise wrapping conventionally are made of a sheet of material folded flat for storage and opened up for use. The walls of the box in such arrangements are folded over the base sheet and unfolded 90 degrees to make a three-dimensional structure. Although this is a satisfactory way of producing a box, it lacks versatility in that each unit can produce only one size of box. Therefore, to accommodate articles of different sizes, a substantial number of sizes of box units are required. Commercially this leads to a large inventory of different items. Flexibility may be lost in selecting the exact correct size for the box that is to be assembled.